Assessment of lake surface dynamics using satellite imagery and in-situ data; case of Lake Ngami in North-West Botswana

Publication date: Available online 3 January 2019Source: Physics and Chemistry of the Earth, Parts A/B/CAuthor(s): Leokeditswe Mokgedi, Joel Nobert, Subira MunishiAbstractThe understanding of surface dynamics of Lake Ngami, a part of Okavango river system is hindered by paucity of data. The aim of this study was to assess the lake surface dynamics using satellite imagery and in-situ data.Surface dynamics of Lake Ngami were monitored using remote sensing methods to complement the available inadequate in-situ measurements. Landsat imagery of the year 1979 to year 2016 were used. The Lake boundary was mapped using the Modified Normalised Difference Water Index (MNDWI), where use was made of Histogram thresholding segmentation method in extracting the water pixels. Remotely sensed actual evapotranspiration (ETa) was estimated using Simplified Surface Energy Balance (SSEB) Modelling Approach; while the satellite derived rainfall estimates were obtained from Tropical Rainfall Measuring Mission (TRMM) 3B43V7 satellite imagery product. Precipitation and potential evaporation data from meteorological stations were used to correct the bias of the satellite products. The SSEB method involved the estimation of evaporation fraction using the MODIS Land Surface Temperature and Emissivity 8-day product (MOD11A2) and GLDAS 0.25° Potential Evapotranspiration version 2.1 for the estimation of potential evapotranspiration.The lake extraction process displayed good results with the average Kapp...

Source: Physics and Chemistry of the Earth, Parts ABC - January 4, 2019 Category: Science Source Type: research